KR20160040695A - System and method for driving an ultrasonic handpiece as a function of the mechanical impedance of the handpiece - Google Patents

Abstract

An ultrasound surgical tool system (30) for operating a handpiece (34) having a tip (50). The voltage and frequency of the drive signal applied to the handpiece driver 40 is a function of the iso value of the current through the mechanical component of the handpiece and the tip and the frequency sensitivity of these components.

Description

TECHNICAL FIELD [0001] The present invention relates to a system and a method for driving an ultrasonic handpiece as a function of the mechanical impedance of the handpiece. BACKGROUND OF THE INVENTION [0002]

The present invention relates generally to an ultrasonically driven surgical handpiece. More specifically, the present invention relates to applying a drive signal to the handpiece as a function of the change in impedance of the mechanical component of the handpiece.

Ultrasonic surgical instruments are useful surgical instruments for performing certain medical procedures and surgical procedures. Generally, the ultrasound surgical instrument comprises a handpiece comprising at least one piezoelectric actuator. A tip is mechanically coupled to the actuator and extends forwardly from the housing or shell, in which the actuator is disposed. The tip has a head. The head is provided with features, often provided with a tooth shape or flute sized to perform a particular medical / surgical task. The ultrasonic tool system also includes a control console. The control console supplies an AC drive signal to the actuator. When a drive signal is applied to a driver, the driver periodically expands and contracts. The expansion / contraction of the actuator induces a tip, more specifically a similar movement within the head of the tip. When the tip moves in this way, the tip is considered to be vibrating. The vibrating head of the tip is applied to the tissue to perform a particular surgical or medical task. For example, some tip heads are applied to the hard tissue. One form of hard tissue is bone. When this type of tip head is vibrated, the forward vibration and the backward vibration of the tip head remove and saw the adjacent hard tissue. Another tip head is designed to be placed against the soft tissue, such that when the tip head vibrates, the tooth shape often removes tissue by a cutting action. Some ultrasonic tools also remove tissue by inducing cavitation in tissue and surrounding fluids. Cavitation occurs as the tip head moves back and forth. Specifically, as a result of this vibration, a small space, a cavity, is formed in the tissue and the surrounding fluid. This cavity is a very small area of extremely low pressure. The pressure difference is developed between the contents of the cells forming the tissue and this cavity. Due to this relatively large pressure difference, the cell wall ruptures. The rupture of these cell walls removes the cells forming the tissue, and removes them.

The heads of ultrasonic tips are often relatively small. Some heads have diameters smaller than 1.0 cm. The ultrasonic tool essentially only removes the adjacent tissue to which the head is applied. Thus, due to the relatively small area of the head, the ultrasonic handpiece has proven to be a useful tool for precisely removing both hard and soft tissue.

In order for an ultrasonic surgical instrument, sometimes referred to as a handpiece or tool, to function efficiently, a drive signal having the appropriate characteristics must be applied to the tool. If the drive signal does not have the proper characteristics, the tip head may experience vibrations below optimal amplitude and / or may not vibrate as soon as possible. When the handpiece is in any state, the ability of the handpiece to remove tissue at a given instant can be significantly reduced.

One means of ensuring that the ultrasonic handpiece works efficiently is to apply a drive signal to the handpiece at the resonant frequency of the handpiece. When the drive signal is at a predetermined voltage or current, application of the drive signal at the resonant frequency results in oscillation in the tip, which is at relatively large amplitude compared to application of the same voltage at the non-resonant frequency.

Other ultrasonic tool systems are designed to apply drive signals at the half-resonant frequency of the handpiece. The antiresonance frequency may be a frequency at which the handpiece has the highest impedance.

Applicant's SONOPET® ultrasonic aspirator includes a console with components designed to generate a variable drive signal and apply the signal to the attached handpiece. There is a resonant circuit in the console. During manufacture of the console, the inductance and capacitance of the resonant circuit are set as a function based on the impedance of the particular handpiece to which the console is intended to be used. The characteristic of the drive signal outputted by the console is set as a function of the voltage across the impedance circuit.

For many procedures, the SONOPET console outputs a drive signal, which is not essentially the same as, but at least close to, the resonant frequency of the mechanical component of the handpiece. However, in many normal use situations, the ultrasonic handpiece is subjected to considerable mechanical load. This can occur, for example, when the tip is pressed against the bone. In this situation, the mechanical load placed on the tip can cause a significant change in the impedance of the mechanical component of the handpiece. When this event occurs, the control console may not be able to output a drive signal at a frequency near the resonant frequency of the mechanical component of the handpiece.

Further, impedance circuits within the console of prior art typically have inductances and capacitances set as a function of the particular handpiece in which the console is used. When handpieces having various internal inductances, capacitances, and resistances are attached to the console, there is a great possibility that the drive signals output by the console will not have features that facilitate efficient operation of the handpieces. This makes it difficult, if not impossible, to use a console designed for use with one handpiece as a power supply to supply the drive signal to another handpiece.

The present invention relates to a new and useful ultrasonic surgical tool system. Within the design limits, the inventive tool system is designed to ensure that the drive signal applied to the system handpiece induces a vibration of the appropriate amplitude in the handpiece tip. More specifically, when various handpieces are attached to the control console, the system can set the driving signal accordingly. As a result of the use of the handpiece, the system also adjusts the characteristics of the drive signal as the impedance characteristics of the handpiece change.

The system of the present invention includes a control console with a handpiece attached thereto. The control console generates a driving signal and supplies it to the handpiece. The control console sets the frequency of the drive signal and the current supplied to the handpiece. The supplied current is set by adjusting the voltage of the driving signal. This feature of the drive signal is set as a function of two variables and one constant. One of the variables is the voltage of the driving signal. The second variable is the current through the handpiece, the current of the drive signal. The constant is the capacitance of one or more piezoelectric actuators in the handpiece.

Based on these three inputs, the control console sets the frequency and voltage level of the drive signal. The frequency of the drive signal is set so as to match the target frequency as much as possible. This ensures that the vibration of the tip head is at the most effective frequency of this vibration. The voltage is set to provide control over the amplitude of the tip head vibration.

In some versions of the invention, the drive signal is adjusted to adjust the equivalents of the current applied to the mechanical components of the handpiece. The frequency of the drive signal can be adjusted to ensure that the drive signal is at a target frequency associated with the resonance and / or anti-resonant frequency of the mechanical component of the handpiece.

The voltage and current of the drive signal are measured by the circuits in the control console. For many subsequent adjustments of the drive signal, this driver capacitance is considered a constant in that the driver capacitance remains unchanged. In some versions of the invention, the driver capacitance is obtained from the data read from the memory integrated with the handpiece attached to the console. Alternatively, based on the query signal set, the console may periodically determine the driver capacitance.

The target frequency of the handpiece is, in part, a function of the mechanical components of the handpiece. The target frequency is also a function of the varying load applied to this component. The target frequency may be the resonant frequency of the mechanical component of the handpiece. In some versions of the invention, the target frequency is the anti-resonance frequency of the mechanical component of the handpiece. In another version of the invention, the target frequency is the frequency between the resonance frequency and the anti-resonance frequency of the mechanical component of the handpiece. In other versions of the invention, the target frequency is outside the band between the resonant frequency and the antiresonant frequency.

Therefore, it is a feature of the system of the present invention that the console selectively adjusts the driving signal. When the addition applied to the handpiece causes a change in the target frequency, the drive signal can be adjusted to remain at or near the target frequency.

It is an additional feature of the present invention that the console can supply a driving signal to a handpiece having a driver with a different capacitance. Likewise, the handpiece of the present invention does not have to be connected to a single specific console.

In some alternative versions of the invention, only the frequency of the drive signal is set. This frequency can be adjusted to ensure that the drive signal causes an equivalent of the current applied to the mechanical component of the handpiece and that the signal is at a frequency near the desired target frequency for this component.

The invention is pointed out in detail in the claims. The above and further features and advantages of the present invention will be understood from the following detailed description taken in conjunction with the following drawings.

Figure 1 shows the basic components of an ultrasonic tool system including features of the present invention.
Figure 2 is a schematic representation of the mechanical components of the handpiece of this tool, system.
Figure 3 is a block diagram of the electrical components of both the handpiece component and the control console of the system of the present invention.
4A and 4B are a representation of the current flow through the handpiece and the impedance of the different components of the handpiece.
Figure 5 shows the data types stored in the memory in the handpiece.
6A and 6B form a flow chart of the operation of the system of the present invention when assembled together.
Figure 7 shows how the impedance circuit formed by the components in the handpiece can be considered to change shape when the handpiece is subjected to a mechanical load.
Figure 8 shows an alternative model of the impedance of the handpiece driver and the equivalent impedance of the mechanical components of the handpiece.
Figure 9 is a graphical representation of the change in reactance of the mechanical reactance with respect to the frequency of the handpiece when the tip is in the air and when the tip is loaded.
10 is a schematic representation of the addition of a variable impedance to a mechanical component of a handpiece.
Figure 11 is a graphical representation of how the addition of variable impedance of a mechanical component of a handpiece affects the reactance of this component.
12 is a block diagram representation of how data can be supplied from a memory integrated with a tip of the present invention to a control console.
Figure 13 shows the data types stored in the memory in the tip.
Figure 14 shows an alternative model of the impedance of the handpiece driver and the equivalent impedance of the mechanical components of the handpiece.
15A and 15B collectively form a flow chart illustrating alternative process steps for adjusting the ultrasonic surgical tool system of the present invention.

I. System Overview and Hardware

An ultrasonic tool system 30 incorporating features of the present invention will now be described generally with reference to Figures 1 and 2. The system 30 includes a handpiece 32. The handpiece 32 includes a body or shell 34 that forms the proximal end of the handpiece. (&Quot; proximal " is understood to mean farther from the point where the handpiece is applied, towards the doctor holding the handpiece. (&Quot; distal " .)

One or more vibrating piezoelectric actuators 40 (shown by four) are disposed within the shell 34. Each driver 40 is formed of a material that undergoes instantaneous expansion or contraction when current is applied to the driver. This expansion / contraction is on the longitudinal axis of the actuator 40, which extends between the guiding surface on the proximal side of the actuator and the guiding surface on the circle. A pair of leads 41 extend away from each driver 40. The leads 41 are attached to the opposite proximal of the driver and to the surface induced on the circle. Many handpieces 32 include a piezoelectric actuator 40 in the form of a disc, but not all handpieces. These drivers 40 are arranged side by side in one line. The lead 41 is a component of the system 30 in which a current in the form of a drive signal is applied to the driver 40. An insulating disk 37, shown in one, separates adjacent leads 41 connected to adjacent drivers 40 from one another. In Fig. 2, the drivers 40 are shown spaced from one another. This is to make the components easier to illustrate. Actually, the insulating disk 37 and the driver 40 are in close contact with each other.

Columns 39 extend longitudinally through insulating disc 37 and driver 40. Columns 39 extend through the driver along the same vertical axis of the driver. The through hole in the insulating disk 37 and the driver 40 is not seen, and the column 39 extends through it. The posts 39 project outwardly relative to both the most proximal actuator 40 and the most distal actuator.

A proximal mass 36 is attached to the proximal leading surface of the driver 40 positioned most proximal. The exposed proximal end section of the column 39 is fixedly attached to the mass 36. If the pillar 39 is threaded, the mass 36 may be a nut.

The horn 42 extends forward from the surface that is guided over the circle of the driver 40 located on the greatest circle. Although not shown, an insulating disk 37 may be present between these components. The cone (42) has a base portion having a diameter approximately equal to the diameter of the driver (40). The diameter of the horn 42 decreases as it extends forwardly from the driver. An exposed distal section of the post 39 is attached to the horn 42. If the column 39 is threaded, the base of the horn can be formed with a threaded closed end hole (unidentified) for receiving the column 39. The handpiece 32 is configured so that the stack of actuators 40 is compressed between the proximal mass 36 and the horn 42. [

A tip 48 extends forward from the distal end of the horn 42. A coupling assembly, shown as a coupling ring 44, typically retains the tip 48 detachably with respect to the rest of the horn 42 and the handpiece 32. The structure of the coupling assembly is not part of the present invention. The tip 48 includes an elongate stem 50. The stem 50 is attached to the horn 42, as part of the tip, through a mating assembly. The stem base 50 extends forward of the handpiece shell 34. The tip 48 is formed with a head 52 at the distal end of the stem 50. Some tip heads 52 have a smooth surface. Some heads 52 are formed with tooth shape 53. The geometry of the head 52 is not part of the invention. The tip head 52 is part of the handpiece 32 applied to a point on the patient where the procedure is performed.

Some tips 48 are provided with a hard tissue, a tooth shape designed to be applied directly to the bone. When this type of type reciprocates, the tooth shape cuts the tissue in the same manner as a conventional saw blade cuts the tissue.

A sleeve 55, shown in Figure 2 as a ring, is typically placed over the tip stem 50. Sleeve 55 typically extends from a location near where the stem portion is attached to the cone 42 to a position about 0.5 cm close to the head 52. Collectively, the handpiece 32, tip 48, and sleeve 55 are configured to define a fluid flow conduit in which the sleeve extends between the outer surface of the tip and the inner surface of the periphery of the sleeve. Sleeve 55 also has a component (not shown) adjacent to the proximal end of the sleeve extending to this conduit. The conduit is open at the distal end of the sleeve. When the handpiece is in use, irrigation fluid flows down the sleeve from the sleeve component and is released adjacent the tip head 52. In some versions of the system, the fluid acts as a medium through which the mechanical vibrations of the tip head are delivered to the tissue. The irrigation fluid also functions as a heat sink for the thermal energy developed by the tip head as a result of vibration of the head.

Although not shown, the tip, horn 42, and handpiece post 39 are often formed together with a conduit defining a fluid flow path from the tip head 52 to the proximal end of the handpiece. When the handpiece is in operation, suction is directed through this conduit. This suction directs the irrigation fluid discharged through the sleeve 55 away from the point where the tip is applied. This inhalation also induces tissue to the tip head. Shortening the distance between the tip head and the tissue improves the transmission of mechanical vibrations from the tip head to the tissue.

The handpiece 32 also includes a memory 58. As discussed below, the memory 58 contains data describing the characteristics of the handpiece. The memory 58 may take the form of an EPROM, EEPROM or RFID tag. The structure of the memory is not part of the present invention. Most handpieces 32 of the present invention include a memory that not only contains data that can be read but also can store data that is written to memory after manufacture of the handpiece. An unillustrated auxiliary component is mounted on the handpiece to facilitate reading data from and writing data to the memory. These components include: Conductor; Exposed contact / contact pins; Coil / antenna; Or an isolation circuit.

The control console 64 is also part of the system 30 of the present invention. The control console 64 supplies a drive signal on the cable 62 to which the handpiece 32 is connected. In many but not all versions of system 30, handpiece 32 and cable 62 are assembled as a single unit. The driving signal is applied to the driver 40. At any given moment, the same drive signal is applied to each driver 40. [ The application of the drive signal causes the driver to simultaneously and periodically expand and contract. The stack of actuators 40 is often between 1 cm and 5 cm in length. The movement distance, amplitude, in a single expansion / contraction period of the actuator can be between 1 micron and 10 microns. The horn 42 amplifies this movement. As a result, when moving from the fully retracted position to the fully extended position, the distal end of the cone 42 and, furthermore, the tip head 52 typically travels up to 1000 microns and typically travels below 500 microns. Some tips 48 are further designed so that longitudinal extension / retraction of the tip stem portion also induces rotational motion in the head. When the handpiece 32 is actuated to cause periodic movement of the tip, the head 52 is considered to be vibrating.

3, the components in the control console 64 include a power source 68. [ The power supply 68 typically outputs a constant voltage signal between 1 VDC and 250 VDC. In many versions of the invention, the maximum potential of the voltage output by the power source 68 is 150 VDC or less. The potential of the signal output by the power source 68 can be selectively set. In the described version of the invention, the power source 68 receives the VOLTAGE_SET (V_S) signal. The power supply 68 establishes the output voltage level as a function of the VOLTAGE_SET signal. The output voltage generated by the power supply 68 is applied to the adjustable amplifier 70. A control signal, specifically a FREQUENCY_SET (F_S) signal, is applied to the amplifier 70. The frequency of the output signal generated by the amplifier 70 is a function of the FREQUENCY_SET signal. An output signal from the amplifier 70 is applied to the filter 72. In some versions of the invention, the amplifier 70 is often a Class-D identifier. An output signal from the amplifier 70 is applied to the filter 72. The filter 72 outputs a sine wave version of the square wave applied from the amplifier 70 to the filter. In some versions of the invention, the filter 72 is a bandpass filter. The signal output from the filter 72 is typically between 10 kHz and 100 kHz. Often, this signal has a minimum frequency of 20 kHz.

The output signal from the filter 72 is applied to the primary winding 78 of the transformer 76 and also to a portion of the control console 64. The voltage present across the secondary winding 82 of the transformer 76 is the drive signal applied to the handpiece driver 40 via the cable 62. This voltage is typically up to 1500 volts AC peak. The drive signal is applied in parallel across the driver 40. More specifically, the drive signal is applied in parallel on both ends of each lead 41 pair.

The transformer (76) includes a teatcler coil (80). A voltage present across the tees of the coil 80 is applied to the voltage measurement circuit 86. [ Based on the signal across the tickle coil 80, the circuit 86 generates a voltage V _s , a signal indicative of the voltage and phase of the voltage of the drive signal applied to the handpiece 32. Coils 90, which are also placed in the control console 64, are located close to one of the conductors that extend from the secondary winding 82 of the transformer. A signal at both ends of the coil 90 is applied to the current measuring circuit 92. Circuit 92 (i _S), the current generates a signal indicative of the magnitude and phase of the current of a drive signal supplied to the hand piece.

V _S and i _S representing characteristics of the drive signal supplied to the piezoelectric actuator 40 The signal is also applied to the processor 96 in the control console 64. The control console 64 also includes a memory reader 102. The memory reader 102 is capable of reading data in the handpiece memory 58. The structure of the memory reader 102 complements the handpiece memory 102. Thus, the memory reader may be an assembly capable of reading data in the EPROM or EEPROM, or an assembly capable of acquiring and reading data from the RFID tag. In versions of the present invention in which data read from memory 58 is read to a conductor, to which a drive signal is supplied to handpiece 32, the memory reader may include an isolation circuit. The data read by the reader 102 is applied to the processor 96.

The processor 96 generates a VOLTAGE_SET signal that is applied to the power supply 68. The processor 96 also generates the FREQUENCY_SET signal applied to the amplifier 70. These signals are control signals that regulate the voltage and frequency of the drive signal supplied by the control console 64. Processor 96 considers this control signal as a function of the characteristics of the handpiece and the obtained measurements V _s and i _s .

An on / off switch is connected to the control console 64. In Fig. 1, the on / off switch is indicated by the foot pedal 104. The state of the pedal 104 is monitored by the processor 96. The on / off switch is a user operation control member for adjusting the on / off state of the system 30. [ In Figure 1, the foot pedal 104 is shown as part of a foot pedal assembly that includes a plurality of pedals. The added pedal can be used to control a device, such as an irrigation pump, a suction pump, or a light. These auxiliary devices are not part of the invention.

The control console 64 is shown having a slide switch 106. As with the switch 104, the state of the switch 106 is monitored by the processor 96. The switch 106 is set by the physician to control the amplitude magnitude of the vibration of the tip head 52. Foot pedal 104 and switch 106 are understood to be generic representations of the input means of the on / off and amplitude setting commands for system 30. In some configurations of the system, a single control member may perform two functions. Thus, when the lever or foot pedal is initially depressed for the first time, the system can be configured so that the tip head undergoes a vibration period of relatively small amplitude. As a result of the continued depression of the lever or foot pedal, the control console resets the drive signal applied to the handpiece, causing the tip head 52 to experience a larger magnitude of vibration period.

A display 108 is mounted on the control console 64. An image on the display 108 is shown to be generated by the processor 96. The information appearing on the display 108 includes information identifying the handpiece and possibly the tip; And information describing characteristics of the operation rate of the system.

II. Operating principle

The components forming the control console 64 are collectively configured to output a drive signal to the handpiece which ideally causes relatively large forward and backward reciprocating vibrations of the tip head 52 . (The amplitude of the head motion is as large as possible because the effectiveness of the tip's ability to remove tissue is generally related to the length of tip head movement relative to the tissue.

One means of creating a large amplitude reciprocating motion of the tip head 52 is to maximize and maintain the current of the drive signal applied to the handpiece within design limits. This is because there is a proportional relationship between the current applied to the handpiece 32 and the amplitude of the motion of the tip head. The current i _S applied to the handpiece can be mathematically regarded as having two components as shown in Figures 4A and 4B: the first component is the current i _O , 40, respectively. The second component is the current i _M , which is the mathematical equivalent of the current applied to the mechanical component of the handpiece 32. The mechanical component of the handpiece is a component of the handpiece that vibrates in response to application of a drive signal. These components include: A proximal mass 36; A column 39; A driver 40; A horn (42) comprising a coupling assembly; And tip 48. The actuator 40 is included as part of this component because the vibrator is part of the vibrating mechanical assembly of the present invention because it is vibrating. Sleeve 55 is typically not considered to be one of these components. This is because the sleeve 55 vibrates, but the sleeve is not part of the vibration system. More specifically, the sleeve 55 can be regarded as a component that places the load on the vibration system.

This system of the present invention is designed to have a constant value of the current (i _M ) of the current applied to the mechanical component, regardless of the impedance change of the handpiece.

The current i _M is determined and controlled based on the impedance of the component forming the handpiece 32. The driver 40 of the handpiece and the mechanical components can be regarded as two impedance circuits connected together in parallel. Where Z _o is the impedance of the driver 40 stack. The driver impedance is essentially a function of the capacitance (C _o ) of the driver 40 and the frequency of the drive signal. This model assumes that the capacitance of cable 62 and any other components that cause the drive signal to be applied to the driver is negligible. Thus, the impedance (Z _O ) has only a capacitive reactance component (1 / jωC ₀ ). The variable "?&Quot; is the angular frequency of the drive signal. The impedance (Z _O ) has negligible resistive reactance components and inductive reactance components.

Impedance (Z _M ) is the mechanical equivalent of the effective impedance of the mechanical component of the handpiece. The impedance Z _M is based on the mechanical equivalent values of the inductance (L _M ), the resistance (R _M ), and the capacitance (C _M ) of the mechanical component of the handpiece. Impedance (Z _H) is the total impedance of the hand piece. The impedance (Z _H ) is therefore calculated according to the formula (1): < EMI ID =

[Equation 1]

For the models of Figures 4A and 4B:

&Quot; (2) "

i _S = i _O + i _M

therefore:

&Quot; (3) "

i _M = i _S - i _O

The current through the driver 40 is calculated according to the following formula:

(4a)

(4b)

.

.

The above is based on the understanding that the stack impedance is based solely on the capacity of the stack and frequency of the driving signal.

therefore,

&Quot; (5) "

. i _M = i _S -

.

In equation (5) and other equations, it is to be understood that the current (i _S ) and the voltage (V _S ) are two vectors, each vector having a magnitude component and a phase component. As discussed above, the driver capacitance (C _O ) is known and constant for the purpose of controlling the drive signal. Assuming that the frequency of the driving signal is relatively constant, the driving current applied to the mechanical component of the handpiece can be kept constant by adjusting the potential of the driving signal V _S.

In addition to adjusting the iso value of the current applied to the mechanical components of the handpiece 32, the system 30 of the present invention adjusts the frequency of the drive signal. More specifically, the drive frequency is adjusted to be at a target frequency based on the resonant frequency of the mechanical components of the handpiece 32. The resonant frequency of a mechanical component is often not the target frequency, but it is not necessarily. The resonant frequency is chosen as the target frequency because, assuming a constant current value, when the mechanical component vibrates at this frequency, the handpiece cycle expansion / contraction (oscillation) is at its maximum amplitude. Special resonant types are referred to as mechanical resonances.

One process in which the frequency of the drive signal can be set in this way is based on the understanding that in mechanical resonance the current flow through the driver 40 stack and the mechanical components must differ in 90 ° phase. This is because the capacitive reactance of the mechanical components of the handpiece and the phase shift effects of the inductive reactance offset each other. In the frequency range in which the drive signal is applied, the actuator has negligible inductive reactance. As a result, the driver induces a 90 [deg.] Phase shift in the current flow not induced from the equivalent value of the current applied to the mechanical component of the handpiece.

The currents (i _O and i _M )

&Quot; (6) "

i _O = Ae ^jθ

And

&Quot; (7) "

i _M = Be ^jφ

As shown in Fig. The constants A and B are proportional to the magnitude of the currents (i _O and i _M ), respectively. Because the phase angle of the current through the mechanical components differs from the current flow through the driver by 90 ° (П / 2 radians) phase:

&Quot; (8) "

Φ = θ - π / 2.

dividing i _O by i _M is the following relationship:

Equation (9a)

Converting the result of equation (9a) to a rectangular coordinate form has the following result:

(9b)

Equation (9c)

=

=

=

The final result of equation (9c) is based on the fact that cosine 90 ° is zero and sine 90 ° is one. This means that when the handpiece is in mechanical resonance, the real component of the ratio of the current flow through the driver 40 to the equivalent value of the current applied to the mechanical component of the handpiece is mathematically zero:

&Quot; (10) "

= 0-Re

= 0

One reason for this ratio being negative is that it makes it possible to normalize the impedance of the handpiece from the resonance ratio -Re = 0.0 to the anti-resonance ratio-Re = 1.0. This facilitates the ease of modeling the performance of the handpiece. Also, as discussed below, assuming that the ratio is negative simplifies the process associated with setting the frequency of the drive signal.

Replacing the equivalent value of the current applied to the mechanical components of the handpiece with the driver current from the above equations (4b) and (5) by the relation of equation (10) means in mechanical resonance that the following relation is true :

&Quot; (11) "

= 0-Re

= 0

The driver capacitance (C _O ) is a constant. By substituting a different frequency into equation (11), the frequency of the drive signal that matches the resonance frequency of the handpiece can be determined by an iterative process. In relation to this process, for a given potential and current, a linear relationship between the frequency and the real component of the ratio of the current flow through the driver 40 to the equivalent value of the current applied to the mechanical component of the handpiece . This implies that by interpolating two different frequencies into equation (11) to determine the ratio, it is possible, by interpolation, to determine a frequency relatively close to the mechanical resonance.

II. Actual operation

)에 대한 데이터는 필드(116) 내에 포함된다. 전류(

)는 종종 1 암페어 피크 미만이고 더 종종은 0.5 암페어 피크 이하이다. 필드(118)는 전류(

), 핸드피스의 기계적인 구성요소에 인가되어야 하는 전류의 최대 등가치를 가리키는 데이터를 포함한다. 전류(

)는 통상적으로, 0.25 암페어 피크 이하이다. 구동 신호의 최대 전위, 전압(

)은 필드(120)에 저장된다. 전압(

)은 종종 1500 볼트 AC 피크이다, To facilitate the operation of the system 30, the memory 58 in the handpiece is loaded with data during assembly of the handpiece. As indicated by the field 112 in FIG. 5, this data includes data identifying the handpiece 32. This data is useful for verifying that the console 64 can apply a drive signal to the handpiece. The data in the field 112 may also indicate the type of information for the handpiece presented on the console display 108. Field 114 contains data indicative of the capacitance (C _O ) of the stack of drivers 40. The driver capacitance may be determined by analysis during the process of assembling the handpiece 34. [ Often, the sum of the capacitances of the actuators is between 500pF and 5000pF. The maximum current and current to be applied to the handpiece (

) Is included in field 116. < RTI ID = 0.0 > electric current(

) Is often less than 1 ampere peak and more often less than 0.5 ampere peak. Field 118 is a current

), And data indicating the maximum value of the current to be applied to the mechanical component of the handpiece. electric current(

) Is typically less than or equal to 0.25 amperes. The maximum potential of the driving signal, the voltage (

Are stored in the field 120. [ Voltage(

) Is often a 1500 volt AC peak,

Further, data indicating the minimum frequency and the maximum frequency of the driving signal to be applied to the handpiece 32 is stored in the handpiece memory. This minimum frequency stored in field 122 is typically the minimum frequency of the drive signal that can be supplied by the control console. The maximum frequency of the drive signal stored in the field 124 is typically between 5 kHz and 40 kHz, which is greater than the minimum frequency.

The field 126 includes a coefficient for filtering the control signal output by the controller 96. In many versions of the invention, the calculation of the VOLTAGE_SET signal and the FREQUENCY_SET signal begins with the calculation of the target value for these signals. PID control loops are used to establish the final level for each of these signals. Field 126 includes a coefficient for each of these control loops. It is understood that data in fields 112, 116, 118, 120, 122, 124 and 126, such as data in field 114, is stored in handpiece memory 58 as part of the process of assembling the handpiece .

The handpiece memory 58 also includes a field 128 as a usage history field. The control console 64 records data in the field 128 to provide a log of the operation of the handpiece during use of the handpiece.

The operation of the system 30 of the present invention is understood with reference to the flow charts of Figures 6A and 6B. Step 140 represents the initial configuration of the system 30. Step 140 includes attachment of the tip 48 to the handpiece 32. If the cable 62 is not integral with the handpiece 32, as part of step 140, the cable is connected to the handpiece 32. A cable 62 is connected to the control console 64 to connect the handpiece to the console. If necessary, a foot pedal 104 is attached to the console 64. Prior to the operation of the handpiece, the physician positions the switch 106 to set the amplitude of the tip head vibration.

Once the handpiece 34 is connected to the control console 64, the console processor 96 reads the data stored in the handpiece memory 58, at step 142, via the memory reader 102. Although not shown and not part of the present invention, any of the check processors 96 may perform to verify that the console 64 is capable of applying a drive signal to the handpiece 32. This check is based on data stored in fields 112 and 128. This check may include: verifying that the handpiece is designed for use with the console; Verifying that the handpiece is activated based on the history of use. Assuming that the handpiece passes this check, the system 30 is ready to use

Step 144 indicates that the processor 94 waits for a signal from the foot pedal 104 or other control member indicating that the doctor wishes to activate the handpiece 32. [ Before the processor 96 receives this signal, the processor does not assert a signal that causes the output of the power signal from the power source 68.

)을 계산한다. 목표 전류(

)는 핸드피스(32)의 기계적인 구성요소에 인가되어야 한다고 프로세서가 결정하는 전류이다. 목표 전류(

)는 팁 진동의 진폭을 조정하기 위해, 핸드피스 메모리로부터 검색된 전류(

) 및 제어(106)의 의사 설정에 기초한다. 목표 전류는 1차 방정식을 사용해서 계산될 수 있다:The doctor operates the handpiece by pressing the control member. In response to receiving a signal that this event has occurred, the processor 96, in step 148,

). Target current (

Is a current determined by the processor to be applied to the mechanical component of the handpiece 32. [ Target current (

) Is used to adjust the amplitude of the tip vibration, the current searched from the handpiece memory (

) And the control 106. [0064] The target current can be calculated using a linear equation:

&Quot; (12) "

= D

= D

The coefficient (D) is between 0.0 and 1.0 (inclusive). For example, if the physician sets the control so that the handpiece tip 50 undergoes a vibration of maximum amplitude, and the handpiece tip desires to engage in vibration with vibration of maximum amplitude, the processor 64 calculates the coefficient D 1. If the setting of the control switch 106 indicates that the vibration is at an amplitude less than the maximum, the processor 64 sets the coefficient D to a value less than one.

)보다 눈에 띄게 작은 구동 신호를 전원이 출력하도록 설정된다. 예컨대, 본 발명의 일부 버전에서, 이 VOLTAGE_SET 신호는 전압(

) 0.02와 0.10 사이인 초기 전위를 구동 신호가 갖도록 설정된다. 더 구체적으로, VOLTAGE_SET 신호는 전압(

) 0.03과 0.07 사이인 전위를 갖도록 설정된다. 전원(68)에 의해 출력된 전압과 구동 신호의 전압(V_S) 사이의 관계는 통상적으로 1차 관계이다. 목표 구동 신호 전압의 함수로서 VOLTAGE_SET 신호의 결정은 목표 구동 신호 전압의 전위 및 프로세서(96)에 이전에 저장된 계수 및 오프셋 값에 기초한다. At step 150, the processor 96 then generates and outputs the VOLTAGE_SET signal. Initially, the VOLTAGE_SET signal is the maximum drive signal voltage retrieved from the handpiece memory 58

The driving signal is set so that the power source outputs a noticeably smaller driving signal. For example, in some versions of the invention, this VOLTAGE_SET signal may be a voltage

) Is set such that the drive signal has an initial potential between 0.02 and 0.10. More specifically, the VOLTAGE_SET signal is a voltage

) ≪ / RTI > between 0.03 and 0.07. The relationship between the voltage output by the power source 68 and the voltage V _s of the drive signal is typically a linear relationship. The determination of the VOLTAGE_SET signal as a function of the target drive signal voltage is based on the potential of the target drive signal voltage and the coefficient and offset values previously stored in the processor 96.

As part of step 150, the FREQUENCY_SET signal is also generated by processor 96 and output. When the control member is initially pressed to actuate the handpiece, the processor 64 generates a FREQUENCY_SET signal which causes the console to output a drive signal at the initial frequency. This initial frequency is the lowest possible frequency at which the drive signal must be applied to the handpiece; The highest possible frequency at which the drive signal should be applied; Or any frequency between the two boundary frequencies.

Although not specifically mentioned, at step 150, the processor exercises any necessary enable signals for the power source 68, the amplifier 70 and any safety components in the console. This signal is generated by outputting a rail signal to the amplifier where the power source 68 is needed and the amplifier 70 outputs the intended square wave and the signal from which the drive signal is derived inductively is transferred to the transformer primary 76 of the transfer 76 And is applied to the winding 78.

As a result of the signal flow across the transformer 76, a drive signal is applied to the handpiece 32. This causes periodic expansion / contraction of the driver 40. This movement of the driver 40 causes the tip head 52 to vibrate. Thus, the sub-steps that occur as a result of the execution of step 150 cause the operation of the handpiece 34. Step 150 is performed continuously until processor 96 determines that the physician desires to deactivate handpiece 32, as discussed below.

The system 30 is then engaged in a feedback control process to ensure that the output drive signal then induces a vibration of the appropriate amplitude within the tip head 52. To perform this control, the system monitors whether the system 96 monitors the voltage (V _S ) of the drive signal through the handpiece, at step 154, which is the output of the voltage measurement circuit 86 Lt; RTI ID = 0.0 > 96 < / RTI > Also at step 154, the processor 96 monitors the current through the handpiece, the current i _s . This is the monitoring of the output signal produced by the current measurement circuit 92.

)의 등가치를 결정한다. 전류(

)는 수학식 5에 기초해서 계산된다. 프로세서(96)는 이 결정을 할 수 있는데, 그 이유는 이 결정이 기초하는 네 가지 변수를 정의하는 데이터를 구비하기 때문이다: 전류 측정 회로(96)로로부터의 전류(i_S); 프로세서가 구동 신호의 주파수를 설정한다는 점에 기초한 주파수(ω); 전압 측정 회로(86)로로부터의 전압(V_S); 및 구동기 커패시턴스 (C _o ). 구동기 커패시턴스(C _o )는 수학식 5에서 변수이나, 핸드피스 메모리(58)로부터 판독되는 고정된 그리고 알려진 변수이다. At step 156, the processor 96 determines the current, current (< RTI ID = 0.0 >

) Is determined. electric current(

) Is calculated based on Equation (5). The processor 96 can make this determination because it has data defining four variables on which this decision is based: current (i _S ) from the current measurement circuit 96; A frequency ([omega]) based on the fact that the processor sets the frequency of the drive signal; The voltage (V _S ) from the voltage measurement circuit 86; And driver capacitance ( C _o ). The driver capacitance C _o is a variable in equation (5), but a fixed and known variable read from handpiece memory 58.

)는 전류(

)과 비교된다. 더 구체적으로, 이 비교는 핸드피스의 기계적인 구성요소를 통한 실제 전류 흐름이 목표 흐름과 동일한지 또는 실질적으로 동일한지를 결정하기 위해 이루어진다. 여기서, 실질적 동일은 전류들이 서로에 대해 20 밀리암페어 이하 이내 및 더 종종은 서로로부터 10 밀리암페어 이하 내일 때의 상태로 간주된다. 시스템(30)의 일부 버전에서, 기계적인 구성요소에 인가되는 전류의 등가치가 50 밀리암페어 밑이면, 전류(

)는 전류 차이가 2 밀리암페어 이하 및 더 통상적으로, 1 밀리암페어 이하인 경우의 전류(

)와 실질적으로 동일한 것으로 간주된다. 대안적으로, 전류들이 서로에 대해 10% 이하 이내이면, 더 바람직하게는 서로에 대해 5% 이하 이내이면, 그리고 이상적으로는, 서로에 대해 1% 이내이면, 이들은 실질적으로 동일한 것으로 간주될 수 있다. At step 158, current (

) Is the current

). More specifically, this comparison is made to determine whether the actual current flow through the mechanical components of the handpiece is the same as or substantially identical to the target flow. Here, substantially the same is considered a state when the currents are less than 20 milliampere for each other and more often less than 10 milliampere from each other. In some versions of the system 30, if the equivalent value of the current applied to the mechanical component is less than 50 milliamperes, the current

) Is the current in the case where the current difference is less than or equal to 2 milliamperes and more typically less than or equal to 1 milliamperes

). ≪ / RTI > Alternatively, if the currents are less than or equal to 10% relative to each other, more preferably less than or equal to 5% relative to each other, and ideally less than or equal to 1% relative to each other, they can be considered to be substantially equal .

If the currents are substantially the same, the system 30 is in one state, where the equivalence of the current applied to the mechanical component of the handpiece is such that the application of the drive signal at the correct frequency is within a suitable Which is a level that induces vibration of amplitude. If the system 30 is in this state, the processor 96 proceeds to step 164.

)가 목표 전류(

)와 실질적으로 동일하지 않다는 것을 가리킨다. 시스템(30)이 이 상태에 있을 때, 단계(160)에서 프로세서(96)는 VOLTAGE_SET 신호를 리셋한다. 더 구체적으로 설명하면, 프로세서(96)는 구동 신호 전압(V_S)를 위한 값을 계산하는데, 이는 수학식 3에 기초해서, 목표 전류(

)와 실질적으로 동일한 핸드피스의 기계적인 구성요소를 통한 조정된 전류 흐름을 야기한다. 단계(160)의 이 계산은 구동기 커패시턴스 및 상수인 구동 신호 주파수에 기초한다. In many situations, the comparison of step 158 may be based on actual current (

) Is the target current

≪ / RTI > When the system 30 is in this state, at step 160, the processor 96 resets the VOLTAGE_SET signal. More specifically, the processor 96 calculates a value for the drive signal voltage V _S , which is based on Equation 3,

Resulting in a regulated current flow through the mechanical components of the handpiece that are substantially the same as the handpiece. This calculation of step 160 is based on the driver capacitance and the drive signal frequency being a constant.

Thereafter, at step 160, based on this new target value for the drive signal potential, the VOLTAGE_SET signal is adjusted and output to the generator 68.

At step 164, the processor determines whether the drive signal is at or substantially at the resonant frequency of the mechanical component of the handpiece. This determination is made by evaluating whether the ratio of Equation (11) is equal to or substantially equal to zero. Here, substantially the same as 0 means that Re is 0.1 or less, preferably 0.05 or less, and more preferably, 0.01 or less.

The comparison of step 164 may indicate that the drive signal applied to the handpiece is at or substantially the same as the resonant frequency of the mechanical component of the handpiece. This is the target state for the drive signal. This means that the driving signal is driving the expansion / contraction of the driver 40 at a frequency that constitutes expansion / contraction so as to have a relatively high amplitude. By extension, this causes the tip head to operate with a relatively high magnitude of vibration.

It may be determined in the evaluation of step 164 that the drive signal is not being applied to the handpiece at or near the resonant frequency of the mechanical component. When the processor 96 makes this determination, in step 166, the processor resets the frequency of the drive signal. Due to the ratio on the left side of Equation 11, which is a negative number, the calculation of step 164 yielding a negative result is interpreted as an indication by the processor 96 that the frequency of the drive signal should increase at step 166. If the calculation of step 164 results in a positive result, there is a handpiece in a state where it is necessary to reduce the frequency of the drive signal to ensure that the drive frequency is closer to the resonant frequency of the mechanical component of the handpiece Processor 96 interprets this result.

The processor 96 resets the frequency of the drive signal applied to the handpiece by adjusting the FREQUENCY_SET signal applied to the amplifier 70. At step 166, the processor assumes that the current i _S , the voltage V _s , and the driver capacitance C _o are constant. In the iterative process, a different frequency is substituted into equation (11). As a result of the new implementation of Equation 11, it can be determined that the real component of the ratio of the current flow through the drive to the equivalent value of the current applied to the mechanical component of the handpiece is less than (or substantially less than) zero. If this condition exists, then at the next iteration, the assigned frequency will be larger than the previously assigned frequency. As a result of the execution and evaluation of Equation (11), it can be determined that the ratio is greater than (or substantially greater than) zero. If this condition exists, then at the next iteration, the assigned frequency will be smaller than the previously assigned frequency. If the ratio is 0 or substantially 0, which is the final result of this calculation, the frequency of the drive signal is set to the assigned frequency. The processor 166 then adjusts the FREQUENCY_SET signal output to the amplifier 70 based on this calculation result. The control console 64 then outputs a drive signal to the handpiece at the resonant frequency of the mechanical component of the handpiece 32, in turn.

)에 의해 명시되는 전위를 초과하지 않는다는 것을 보장하기 위해 VOLTAGE_SET 신호의 조정이 제한된다. 핸드피스에 인가되는 구동 신호의 전류가

를 초과하지 않으며 전류의 기계적인 성분이

를 초과하지 않는다는 것을 보장하기 위해 VOLTAGE_SET 신호의 조정이 더 제한된다. Although not shown, it should be understood that the characteristics of the drive signals applied to the handpiece 32 are limited by the boundary parameters read from the handpiece. More specifically, when the driving signal is at the maximum frequency level (

The adjustment of the VOLTAGE_SET signal is limited to ensure that it does not exceed the potential specified by the VOLTAGE_SET signal. The current of the driving signal applied to the handpiece is

And the mechanical composition of the current does not exceed

Lt; RTI ID = 0.0 > VOLTAGE_SET < / RTI >

)를 재계산하는 프로세스 및 구동 신호의 전위 및 주파수를 선택적으로 조정하는 프로세스가 시스템이 작동된 채로 남아있는 한 일반적으로 수행되기 때문이다. In Figures 6A and 6B, after execution of step 160, or if necessary, after execution of step 164, the system is shown as returning to step 144. [ This means that the target current

) And the process of selectively adjusting the potential and frequency of the drive signal are generally performed as long as the system remains operative.

)의 변화를 야기한다. 시스템(30)은 이 변화들을 측정값(V_S 및 i_S)에서의 변화들로서 검출한다. 따라서, 단계(164)가 수행된 후에, 단계(158)의 다음 평가는 아마도, 시스템이 전류가 목표 전류(

)로부터 변이된 상태에 있다는 것을 가리킬 것이다. 이는 구동 신호의 전압의 크기를 조정하기 위해 단계(160)의 새로운 실행을 필요로 할 것이다. There are a number of reasons why the control loop is iteratively executed. In general, it should be appreciated that, as a result of the adjustment, if the frequency of the drive signal is adjusted, there will be a change in the impedance of the two driver impedances (Z _O ) and impedance (Z _M ) of the mechanical component of the handpiece. This is due to the current flow through the handpiece, and more specifically, the current through the mechanical component of the handpiece

). ≪ / RTI > The system 30 detects these changes as changes in the measured values V _S and i _S. Thus, after step 164 has been performed, the next evaluation of step 158 may be that the system determines that the current is below the target current

Quot;). ≪ / RTI > This will require a new run of step 160 to adjust the magnitude of the voltage of the drive signal.

Similarly, adjustment of the potential of the driving signal will also cause a change in voltage V _s and current i _s . This means that when step 164 is executed, the evaluation will indicate that the drive signal is no longer at the resonant frequency of the mechanical component of the handpiece.

과 실질적으로 동일한 그리고 핸드피스의 기계적인 구성요소의 공진 주파수에 있는, 핸드피스의 기계적인 구성요소을 통한 전류 흐름을 야기한다. 시작시에, 팁 헤드가 조직에 인가되지 않는다고 가정하면, 시스템은 2초 이하 뒤에, 더 종종은 1초 이하 뒤에 이 상태에 도달한다고 여겨진다. After a plurality of cycles through the control loop, the console 64 exerts a drive signal,

And at the resonant frequency of the mechanical component of the handpiece, resulting in a current flow through the mechanical component of the handpiece. At the start, assuming that the tip head is not applied to the tissue, the system is considered to reach this state after 2 seconds or less, more often after 1 second or less.

An additional reason for the control loop to be executed continuously is that it must deal with the characteristics of how the handpiece 32 is employed. For the handpiece to function, the head 52 is positioned relative to the tissue (not shown). This is because there is a back and forth movement of the tooth shape to the tissue causing the sawing and removal of the tissue. Again, in some embodiments of the present invention, this anteroposterior movement is one that causes fluid adjacent to the tissue, and in some instances, cavitation of the tissue itself.

When the head is positioned against the tissue, the mechanical load is placed over the component forming the handpiece. This mechanical load changes the impedance of the mechanical load of the handpiece. Also, when the system 30 is operated, the temperature of the mechanical components of the handpiece often changes. This change in component temperature causes a change in the properties of these components. Changes in component temperature can cause variations in the target frequency. This variation in the characteristics of the mechanical components of the handpiece is shown in Fig. 7 by changing the inductance (L _M ), the resistance (R _M ), and the capacitance (C _M ), respectively.

) 두 가지 모두의 흐름에서 변화를 야기한다. 제어 루프의 계속적인 실행은 따라서, 임피던스에서 이러한 변화가 발생할 때, 전류의 기계적인 성분이 목표 전류(

)와 실질적으로 동일하고 구동 신호의 주파수가 핸드피스의 기계적인 구성요소의 공진 주파수와 실질적으로 동일하다는 것을 보장하기 위해 구동 신호가 리셋된다는 것을 보장한다. 이 목표 파라미터와 가까운 구동 신호의 특징의 유지는, 팁 헤드(52)가 노출되는 기계 부하가 변함에 따라, 헤드의 진동의 진폭이 실질적으로 일정하게 남아있는 것을 보장한다. The resulting change in impedance and resonance frequency is due to the current through the handpiece (i _S ) and the current through the mechanical component

) Causes a change in both flows. The continual execution of the control loop is thus such that when such a change in impedance occurs, the mechanical component of the current becomes the target current

) And ensures that the drive signal is reset to ensure that the frequency of the drive signal is substantially equal to the resonant frequency of the mechanical component of the handpiece. The maintenance of the characteristic of the drive signal close to the target parameter ensures that the amplitude of the vibration of the head remains substantially constant as the mechanical load to which the tip head 52 is exposed is changed.

)는 이전에 계산된 목표 전류와는 상이할 것이다. 이는 차례로, 아마도, 단계(158)의 다음 실행 결과, 전류(

)가 더이상 목표 전류(

)와 실질적으로 동일하지 않다고 결정될 것이라는 것을 의미한다. 위에서 개시된 이유로, 이는 아마도, 구동 신호의 전의 및 주파수의 조정을 야기할 것이다. Further, during the time period during which the handpiece 32 is actuated, the physician may wish to adjust the amplitude of the tip head vibration. This adjustment is caused by a reset of the switch 106 or similar control member. Once the adjustment occurs, in a subsequent execution of step 148, the newly calculated target current (< RTI ID = 0.0 >

) Will be different from the previously calculated target current. This, in turn, presumably results from the next execution of step 158,

) Is no longer the target current (

≪ / RTI > For the reasons described above, this will probably lead to the adjustment of the frequency of the drive signal and before.

Thus, the control loop described above starting with the evaluation of step 144 is executed continuously as long as the foot pedal 104 or other on / off control remains activated. The physician deactivates the handpiece by releasing the foot pedal 104. [ This causes, in one of the subsequent executions of step 144, the processor to receive a signal that the control member is in the off position. In response to the processor 96 receiving this signal, a step is not shown, but the processor invalidates the signaling that was exercised to cause the output of the drive signal. The system 30 returns to the continuous monitoring of signals from the on / off control member to determine if the doctor wants to activate the handpiece 32. [

The system 30 of the present invention is configured such that due to the repeated execution of steps 164 and 166 the system maintains the drive signal at a frequency substantially equal to the resonant frequency of the mechanical component of the handpiece 32. [ This relationship is maintained when the resonant frequency of the mechanical component of the handpiece changes due to a mechanical load and / or a temperature change of the component. Thus, the system invention can vibrate the tip of the tip at the desired amplitude, even when the tip and other components of the handpiece are subjected to a mechanical load or experience a temperature change. This reduces the need for surgical personnel to use a system that continuously adjusts the drive signal to ensure that the tip head vibrates continuously at the desired amplitude.

Also, during the procedure, the tip head can be depressed against the tissue abruptly. This causes a rapid, significant increase in the impedance of the mechanical components of the handpiece. In response to this rapid change in impedance, the system 30 of the present invention quickly adjusts the potential and frequency of the drive signal. Adjustment of this feature of the drive signal serves to ensure that the tip head oscillation maintains the desired amplitude. This reduces the degree to which the sudden mechanical load of the handpiece causes a similar sudden decrease in amplitude of tip head vibration.

An additional feature of system 30 is that it does not track to a particular phase relationship between the voltage and current of the drive signal. Instead, system 30 tracks the phase of the equivalent value of the drive signal applied to the mechanical component of the handpiece. For the reasons discussed above, this ensures that the supplied drive signal has the characteristic of maintaining the mechanical resonance of the handpiece.

The system 30 of the present invention is further configured such that control of the handpiece is not based on matching of the capacitance, resistance, or inductance of the components within the control console based on the characteristics of the handpiece. This means that a single console 64 can be used to configure the system 30 of the present invention with each handpiece having a different handpiece with its driver capacitance. The console configures this system for each handpiece based on data read from the handpiece memory 58 that describes the driver capacitance. Likewise, handpieces can be used with different control consoles to assemble the system 30 of the present invention.

The system 30 of the present invention is further designed to apply a current equivalent value to a mechanical component of the handpiece that is substantially the same as the target current. This target current is based on a physician's setting of the desired amplitude of tip head vibration. Thus, the system of the present invention provides the physician with a relatively accurate means of controlling the amplitude of the tip head vibration.

IV. First Alternative Method of Driving Signal Frequency Control

In an alternative configuration of the system 30 of the present invention, the target frequency of the drive signal is set to the anti-resonance frequency of the mechanical component of the handpiece. This anti-resonance frequency is a frequency at which the impedance of the handpiece 32 is at its maximum. Ideally, this is infinite.

In this version of the present invention, at step 164, the real component of the ratio of the current supplied to the piezoelectric actuator 40 to the equivalent value of the current applied to the mechanical component of the handpiece 32 is evaluated as follows do.

&Quot; (13) "

= 1 -Re

= 1

If the evaluation of step 164 does not cause the ratio to be substantially equal to 1, then the processor substitutes the different frequencies in equation (166). This process continues until the processor determines a frequency that is substantially equal to one. This frequency is anti-resonance frequency. The processor then outputs a FREQUENCY_SET signal, which causes the control console to supply a drive signal at this frequency.

In other versions of the present invention, the processor 96 may determine the current supplied to the piezoelectric driver 40 for a target frequency that is different from the resonant or antiresonant frequency and the current applied to the mechanical component of the handpiece 32 The real component of the ratio of the value can be evaluated. Thus, the estimate may be a value between 1 and 0 or a value much greater than one.

V. Second and Third Alternative Methods of Driving Frequency Control

For some configurations of the system 30 of the present invention, the circuit of Figure 4b is a highly simplified view of the impedance of the mechanical components forming the handpiece. For this version of the invention, as shown mathematically in FIG. 8, the mechanical components of some ultrasonic tools may be considered to include a plurality of RLC series connection circuits coupled together in parallel. This means that these components have a plurality of frequencies that are in resonance over the frequency range; The reactive component of the impedance is zero. The impedance Z _H of this type of handpiece 32 and tip 48 is expressed as:

&Quot; (14) "

,

. . .

,

. . . .

및

,

　.　.　.　

는 각각, 핸드피스의 기계적인 구성요소의 RLC 브랜치 각각의 인덕턴스, 저항, 및 커패시턴스이다.

,

. . .

,

. . . .

And

,

. . .

Are the inductance, resistance, and capacitance, respectively, of the RLC branch of the mechanical component of the handpiece.

If there are a plurality of resonance frequencies within the frequency range in which the drive signal is applied to the handpiece, it may be difficult to apply the drive signal to this type of handpiece and tip assembly. The essence of this problem is understood with reference to Fig. Here, the plot 182 represents the reactance over the frequency range for the mechanical component of the handpiece when the tip is operated in air. The drive signal is applied to the handpiece over the frequency range from 25.20 kHz to 25.65 kHz, over the area in the two thick vertical lines 181 and 183 of Fig. Within this frequency range, the reactive component of the mechanical impedance intersects the zero reactance point approximately once at 25.54 kHz. The mechanical reactance of the handpiece also crosses the zero reactance point at approximately 25.86 kHz, outside of the drive frequency range. However, since there is a second crossing outside the range in which the control console 64 applies the drive signal, the point at which the mechanical reactance is zero at this frequency does not affect the operation of the system.

Plot 184 shows the change in reactance of the mechanical component of the handpiece over frequency during vibration, when the tip is pressed against the load. This load is understood as an organization in which the tip is intended to be removed. As discussed above, this results in changes in the equivalent resistance and reactance of the mechanical components forming the handpiece. The reactance at a given frequency changes from plot 182 to plot 184. Here, it can be seen that within the frequency range to which the drive signal is applied, the equivalent reactance of the mechanical components of the handpiece can cross at the zero reactance point at 25.30 kHz and 25.45 kHz twice.

이는 플롯(184)의 예를 위해, 구동 주파수가 25.45kHz보다 더 큰 경우 위에서 논의된 바와 같이 단계(164)를 실행할 때 이 결과가 반환된다는 것이다. 이것이 단계(164)의 평가 결과이면, 단계(166)의 실행에서, 제어 프로세서(66)는 구동 신호의 주파수를 증가시킨다. 이는 구동 신호가, 실제로는 구동기(40)가 원하는 목표 주파수로부터 더 멀리 있는 주파수에서 핸드피스의 기계적인 구성요소를 진동하게 한다. In order for the particular handpiece and tip assembly to function most efficiently, it is typically desirable to apply the drive signal at a lower or nearer of the two resonant frequencies. The lower of the two resonant frequencies is thus the target frequency. In some instances when step 164 is executed, the evaluation result of step 164 may return the following result:

This is for the example of plot 184, if the drive frequency is greater than 25.45 kHz, this result is returned when executing step 164 as discussed above. If this is the evaluation result of step 164, in execution of step 166, the control processor 66 increases the frequency of the drive signal. This causes the drive signal to vibrate the mechanical components of the handpiece at a frequency that is actually farther from the target frequency of the driver 40. [

To reduce the likelihood that the event identified above will occur, in some versions of the invention, the system selectively adds the imaginary impedance (X _adj ) to the impedance of the mechanical component of the handpiece. In general, the virtual impedance X _adj appears to be in series with the mathematical model of the impedance of the mechanical component of the handpiece, as shown in Fig.

11 shows the effect of adding this virtual impedance to the impedance of the mechanical component of the handpiece. In Fig. 11, plot 184 is the same plot of reactance of the mechanical components of the handpiece when the tip is under load, as shown in Fig. The plot 185 is the reactive component of the imaginary impedance X _adj . Here, at a frequency where the reactance of the mechanical component of the handpiece is zero, the reactive component of the virtual impedance is assumed to be zero. The plot 186 is the reactance sum of the plots 184 and 186. As plot 186 shows, when the virtual reactance is added to the mechanical reactance, the total reactance has only a single zero crossing in the frequency range over which the drive frequency is applied.

Figure 12 is a block and partial view of an alternative component of a version of the invention designed to add a virtual impedance to the actual impedance of a mechanical component of a handpiece. The hand piece 190 shown in a rectangle has the same characteristics as the hand piece 32 described previously. This feature includes conductive sockets or other contacts 196 and 198 where the drive signal is supplied to the driver 40 in the handpiece. The drive signal is supplied from pins or other conductive contacts 188 and 189 that are integral with the control console socket to which the handpiece is connected. For ease of illustration, cable 62 is not visible in FIG.

The specific memory 58 in the handpiece 190 is an RFID tag. Because the memory 58 is an RFID tag, a coil or antenna 202 is also connected to the display and memory 58 within the handpiece 190. It is understood that the coil 202 is within the termination of the cable connected to the control console socket. The coil 202 is configured and positioned to inductively exchange signals with a complementary coil 187 disposed within the console socket. Although not shown, the console coil 187 is connected to the console memory reader 102. The memory reader 102 converts the signal received via the coil 187 into a signal that can be read by the processor 96. The memory reader 102 also outputs to the handpiece memory 58 data that the processor 96 wants to be written to memory.

A second coil, coil 206, is also disposed within the handpiece 190. While the coil 202 is typically positioned adjacent to the proximal end of the handpiece 190, the coil 206 is typically positioned adjacent the distal end. More specifically, the coil 206 is positioned to exchange signals with the sleeve coil 212 discussed below. The conductor 204 in the handpiece 190 connects the coil 202 with the coil 206.

The sleeve 55 to which the tip 48 extends appears as a tapered unit in Fig. A tip memory 214 is disposed within the sleeve 55. The memory 214 is referred to as a " tip memory " although the memory 214 is within the sleeve 55 for two reasons. First, the tip 48 and the sleeve 55 are typically packaged together as a kit, while they are separate components. Secondly, the data contained in the memory 55 is mainly used to control the operation of the tip 48. The coil 212 inserted in the sleeve 55 is connected to the tip memory 55.

13 shows a part of the data stored in the tip memory 214. Fig. The tip identification data field 218 includes tip identification data that is similar to the handpiece identification data in the field 112. There are minimum and maximum current fields 220 and 224. Fields 220 and 222 contain data indicating a range of iso-values of current that the memory 214 should be applied to the mechanical components of the handpiece for the particular tip with which it is associated. A maximum voltage field 224 similar to the maximum voltage field 120 is present in the handpiece memory. There are drive frequency fields 226 and 228. The data in the fields 226 and 228 may specify a tip specific frequency range for the drive signal, which may be the handpiece memory, the maximum and minimum drive frequency fields 122 and 124, It may be different from the frequency range. The PID coefficient field 230 includes a filtering coefficient for the control signal that may be more specific than the data in the handpiece PID coefficient field 126 for the tip. The tip usage history field 232 contains data on usage of the tip. The console processor 96 via the memory reader 102 may write the data to the field 232.

The tip memory also includes a target frequency field 234, and an impedance adjustment factor field 236. [ The target frequency field 234 includes data representing a frequency (? _Target ) within the frequency range of the drive signal applied to the handpiece. More specifically, the frequency? _Target is a frequency within the range of the driving frequency of the handpiece where the mechanical reactance is at a minimum when the tip is under load. It should be understood that the load at which the tip is exposed varies between procedures and even within a single procedure. This means that the frequency at which the mechanical reactance of the handpiece is at a minimum is not a constant, between procedures and within the procedure. The frequency ([omega] _target ) Is the frequency within the range expected. The coefficient field 236 includes the coefficient m described above that defines the change in reactance over frequency.

The inventive system to which the handpiece 190 is attached is generally driven in the same manner that the handpiece 32 is driven. Nevertheless, there are some differences in process steps as described in Figures 6A and 6B. At step 142, the control processor 96 reads more data in the handpiece memory 58. In addition, at step 142, the control processor reads the data in the tip memory 214.

Steps for determining whether the system can vibrate tip 48 based on data in handpiece memory 58 and tip memory 214 are not shown. Data indicating that the system is unsuitable for vibrating the tip includes data indicating that the tip has been used for more than its designed life. Other data indicating that the system should not vibrate the tip include identification data from the handpiece and the tip collectively indicating that the tip is not the tip the handpiece is intended to vibrate. If the system is not suitable for driving the tip in the current configuration, the control processor 96 typically determines that the information is presented on the display 108, indicating that the console will not supply a drive signal to the handpiece 190 do. In some versions of the invention, this information is presented as a warning only. After this information is presented, the doctor is still given the opportunity to operate the handpiece.

)를 설정한다. 구동 신호의 주파수 범위는 메모리(214)로부터 또한 검색되는 주파수 범위에 기초해서 설정될 수 있다. At step 148, the processor 94 determines the target current (i. E., Based on the maximum current value retrieved from the tool memory 214)

). The frequency range of the drive signal may be set based on the frequency range that is also retrieved from the memory 214. [

An additional change in how the characteristics of the drive signal is determined occurs when step 164 is performed. In this version of the invention, the control processor 96 does not use the evaluation of equation (11) to determine whether the mechanical component of the handpiece is resonant. Instead, the processor uses the following formula to evaluate whether the mechanical components of the handpiece are in resonance:

&Quot; (15) "

+m(

) = 0.-Re

+ m (

) = 0.

Here,? _Target is the target resonance frequency read from the tip memory field 234. The coefficient m is a coefficient that sets the slope for establishing the virtual impedance as a function of frequency. This is a coefficient read from the tip memory field 236. [ The variables m and [omega _target ] thus define the zero crossing and slope of the reactive component of the imaginary impedance, as shown by plot 185 in Fig. With the addition of the m (? -? _target ) component, the scalar on the left hand side of Equation (15) can be regarded as a modified ratio compared to the ratio of Equation (11).

The inclusion of the imaginary impedance in the evaluation of step 164 is advantageous if the drive signal needs to be reduced or increased if there is a plurality of zero crossings of the reactance of the real component among the mechanical components of the reactance in the frequency range of the drive signal And that the evaluation will still point to the desired resonant frequency. Thus, using the example of plot 186, if the evaluation of this version of step 164 is negatively tested, it clearly means that the frequency must be increased to drive the signal to resonance. Similarly, if the evaluation is tested positively, the frequency of the drive signal is clearly reduced.

This version of the invention is also useful when the physician first places the tip head 52 in the tissue and then desires to operate the handpiece 32. In this situation, the handpiece and tip are already under load when actuated. Due to their mechanical nature, some tips have a feature that, when started under load, the resistance of the load immediately attenuates the vibration to essentially non-vibrational levels. When the handpiece and tip are in this condition, the system can be considered essentially in a stall state. When the system is in this state, the reactance of the mechanical components of the handpiece is essentially constant over the range of drive frequencies. In essence, the mechanical, resistive component of the impedance becomes significantly larger than the mechanical equivalent of the inductive and capacitive impedances. This means, for example, that changes in reactance along the frequency as indicated by the plot 184 are difficult to detect.

Thus, in this version of the present invention in which this condition exists, the steering component of Equation (16) becomes the main component of the rate varying with frequency. Thus, at the time of execution of step 164, if the handpiece and tip must be stopped, the processor still obtains some indication of how close the drive frequency is to the drive frequency required to drive the tip at resonant frequency under load. In practice, what happens when the system is in this condition is that the processor increases the frequency of the drive signal. This increase in frequency of the drive signal causes the handpiece driver and tip to oscillate at a frequency that causes the handpiece to deviate from the stall state.

It should be appreciated that it may not be necessary to consider the virtual impedance for every tip that may be integrated with the system of the present invention. For such a tip that does not require adjustment, the impedance adjustment coefficient m is set to zero. This causes Equation (15) to be reduced to Equation (11).

In a fourth alternative version of the invention, the addition of this imaginary impedance is used to adjust the setting of the frequency of the drive signal so that the drive signal is at the anti-resonant frequency of the impedance of the mechanical component of the handpiece. Thus, Equations (13) and (15) are combined as follows:

&Quot; (16) "

+ m(

) = 1.-Re

+ m (

) = 1.

In still another version of the invention, the modified ratio on the left hand side of Equations 15 and 16 can be compared to a target ratio representing the frequency between the resonant frequency and the antiresonant frequency.

VI. A fourth alternative means of driving frequency control

In still another version of the invention, only the frequency of the drive signal is adjusted. In this version of the invention, the frequency of the drive signal is adjusted such that the desired target for the equivalent value of the current which is at or near the resonant frequency of the mechanical component of the handpiece and which must be applied to the mechanical component of the handpiece Or at a current level close thereto.

This version of the invention is understood with reference to the flow charts of Figures 15A and 15B. In this version of the invention, steps 140, 142, 144, 148, and 154 are performed substantially the same as discussed above for the process depicted in the flow charts of FIGS. 6A and 6B. In this version of the invention in which the handpiece is initially operated, step 150A, which is an alternative to the previously described step 150, is performed when the handpiece is initially actuated. At step 150A, the processor 96 outputs a VOLTAGE_SET signal indicating the highest voltage that should be applied to the handpiece. The processor 96 also generates and outputs a FREQUENCY_SET signal. The same process used to determine the initial FREQUENCY_SET signal in step 150 may be used in step 150A to output the same signal in step 150A. After step 154 is executed, in this method of the present invention, at step 252, the processor calculates the ratio of the current flow through the driver 40 to the equivalent current flow through the mechanical components of the handpiece, Calculate the ratio on the left side of Equation 11. In step 254, this ratio is compared to the target ratio TF. Initially, the target rate is a scalar value that represents the desired target frequency of the drive signal for the mechanical component of the handpiece. For example, if it is necessary to drive a mechanical component of a handpiece at a resonant frequency, the initial target rate is zero. For example, if it is necessary to drive a mechanical component of a handpiece at an antiresonant frequency, the initial target rate is one. The initial target rate can be between these values. This may be the case where the mechanical components of the handpiece have a sensitivity between the sensitivity at the resonant frequency and the sensitivity at the anti-resonance frequency.

Based on this comparison, the frequency of the drive signal is optionally reset in step 256, if necessary. This analysis and reset of FREQUENCY_SET is analogous to the analysis and frequency reset of steps 164 and 166.

)를 결정한다. 단계(258)는 단계(156)와 유사하다. 단계(260)에서, 이 계산된 전류는 목표 전류, 전류(

)와 비교된다. 단계(260)는 단계(158)과 유사하다.Step 254 and then, if necessary, after step 256 has been executed, then in step 258 the processor determines the equivalent current flow through the mechanical component of the handpiece,

). Step 258 is similar to step 156. In step 260, the calculated current is the target current, the current (

). Step 260 is similar to step 158.

When the calculated current is relatively close to the target current, the processor 96 determines that the drive signal is at a frequency substantially the same as the desired target frequency for the mechanical component of the handpiece, and the equivalent current through the component Determine that the system is in a situation that is substantially the same as the goal of value. If the system is in this state, the processor returns to step 144. This recall is similar to the return to step 144 performed after step 164 or step 166 is performed.

As a result of the execution of step 260, it can be determined that there is a substantial difference between the calculated current and the target current. In many situations, this is because the calculated current is higher than the target current. If the system of the present invention is in this state, at step 262, the processor adjusts the value of the target rate. This new rate is TR ^ADJ . This is because subsequent resetting of the drive frequency away from the target drive frequency will cause a similar decrease in the equivalent value of the current applied to the mechanical component of the handpiece.

In step 264, the ratio of current through the actuator to the equivalent value of the current flow through the mechanical component of the handpiece is compared to the adjusted target rate. Perhaps this comparison will indicate that the actual ratio is substantially different from the adjusted target rate. In this situation, at step 266, the processor adjusts the FREQUENCY_SET signal. This FREQUENCY_SET signal is reset to bring the new drive signal closer to what is needed to cause the iso value of the current applied to the mechanical component of the handpiece to be reset to a level that reaches the goal for this equivalent current. If the difference between the initial target current and the adjusted target current is insignificant, step 266 may not be performed.

After execution of step 264 and sometimes after execution of step 262, the processor 96 returns to execution of step 144. [

This version of the present invention allows for the equal value of the current at a frequency close to the desired target frequency for the handpiece and applied to the mechanical components of the handpiece to be set for the current flow A driving signal is supplied to the handpiece which is close to the target.

VII. Alternative / additional means of obtaining driver capacitance

In an alternative version of the present invention, there is a circuit in the control console 64 that is capable of measuring the capacitance ( C _o ) of at least one piezoelectric actuator. For example, the capacitance can be obtained by outputting a driving signal that continues over a frequency range. During this time period, the measurements V _S and i _S are generated for the drive signals having different frequencies. Based on this data, the processor 96 mathematically determines the driver capacitance C _o .

The system 30 of the present invention can be configured to perform this capacitance determination process to eliminate the need to provide the handpiece with a memory containing data describing the driver capacitance. In this version of the invention, the system determines the drive capacitance as part of step 140, the initial configuration of the system.

There is also a reason to provide this capability to the system 30 to determine the driver capacitance even when the system can obtain data describing the capacitance value of the driver from the memory associated with the handpiece. One reason that it is desirable to provide this capability to the system and allow the system to perform this process is to determine the operating state of the handpiece. Specifically, the system may be configured to perform this step and to compare the driver capacitance generated by the processor with the capacitance value obtained from the handpiece memory, the value obtained in step 142. If this capacitance value is not substantially the same, the processor interprets this difference as indicating that the handpiece may be in a malfunctioning state. This malfunction can be caused by some type of damaging actuator. The processor will then issue a message indicating that the handpiece can not function properly. The doctor can then use this information to determine if it is appropriate to proceed with this particular handpiece.

In both configurations of the present invention, the system can be further configured to determine the driver capacitance even after the procedure has begun. As mentioned above, the driver capacitance is substantially constant for the purpose of supplying the drive signal in accordance with the present invention. Nonetheless, there may be situations in which the driver capacitance may change over time during the procedure. For example, if the handpiece is used for an extended period of time, 10 minutes or more, the handpiece comprising the driver 40 may be affected by the friction induced heating. This heating is the result of repeated expansion and contraction of the driver 40. The temperature variation of the handpiece can cause a change in the driver capacitance. Thereby, even when the initial capacitance is read from the handpiece memory 58, the system can periodically execute the process to determine the driver capacitance.

In this configuration of the invention, if the determined driver capacitance is within the set range of the previous capacitance, the processor 96 uses the newly determined driver capacitance as the variable driver capacitance C _o to set the characteristics of the drive signal. However, there may be situations where the newly determined driver capacitance is outside the range set for the previous driver capacitance. The processor 96 may be configured to interpret the system 30 in this state as an indication that the handpiece 32 has entered a malfunctioning state. If the processor 96 makes this determination, the processor may cause the message to be displayed indicating that the handpiece may be in this state.

VIII. An alternative model of the impedance of the mechanical components of the handpiece

In an alternative configuration of the present invention, the model of the current applied to the driver 40 and the equivalence of the current applied to the mechanical components of the handpiece are based on an alternative model of the resistance, inductance, and capacitance of this component .

Figure 14 shows one alternative model of the arrangement of components of a handpiece presenting the impedance to the equivalent value of the current and the applied current. In this model, the capacitance has two components, the combined capacitance (C _A ) and the mixed capacitance (C _X ). Each of these capacitances is a function of both the driver capacitance and the equivalent capacitance of the mechanical components of the handpiece 40, as shown by equations (14) and (15).

&Quot; (17) "

C _A = C _O + C _M

&Quot; (18) "

C _X =

The inductance is the mixed inductance (L _X ). This inductance is a function of the equivalent inductance of the mechanical component of the handpiece, the equivalent capacitance of this component, and the driver capacitance. Equation 19 is one means for determining the mixed inductance:

&Quot; (19) "

_. L _X = L _M

_.

The resistance is the mixed resistance (R _X ). As indicated by equation (17), the mixing resistance is a function of the equivalent resistance of the mechanical component of the handpiece, the equivalent capacitance of this component, and the driver capacitance:

&Quot; (20) "

_. R _X = R _M

_.

This implies that there is a similar variation in the equation used to calculate the handpiece impedance, the equivalent value of the current applied to the mechanical component of the handpiece, and the real component of the ratio of the equivalent current flow through the mechanical component of the handpiece .

Further, although not illustrated, in other models of the equivalent impedance of the mechanical components of the handpiece, it should be understood that two of the three impedance contribution components, the resistance, the inductance, or the capacitance, may be in parallel with each other. In this model, the third component is in series with two parallel components.

IX. Additional alternative versions

The above relates to a specific version of the present invention. Some versions of the invention may have features that are different from those described. For example, the aforementioned features of different versions of the invention may be combined.

The structural features of the present invention may also be different from those described. For example, the column on which the actuator is disposed can be machined with a horn. Similarly, other means may be used to measure the voltage across the handpiece and the current through the handpiece. Thus, in contrast to inductors, resistors can be employed to perform this signal sensing. In many versions of the invention, an insulating disk may not be present between adjacent drivers. The insulating component may be between the proximal actuator and the mass 36 or between the actuator and the horn. The number of actuators may be less or greater than the number of actuators disclosed.

In some versions of the invention, the signal foot pedal or hand switch is a control member, which is used to control both the on / off state of the handpiece and the magnitude of the drive signal applied to the handpiece.

Likewise, the electrical components of the system may be different from those described. For example, some versions of the control console may not include Class-D amplifiers. In one alternate version of the invention, the signal output by the power source is output to a Class-A amplifier. In one embodiment of this version of the invention, the processor 96 still outputs a VOLTAGE_SET signal to the power supply 68 to establish the peak voltage of the drive signal. The processor 68 also outputs a variable frequency sine wave signal to the amplifier as a FREQUENCY_SET signal. Based on this FREQUENCY_SET signal, the amplifier selectively amplifies the signal from the power supply to supply a drive signal having a desired frequency. In still another embodiment of this version of the invention, the power source outputs a DC signal at a fixed potential. The processor produces a sine wave with both frequency and peak-to-peak voltage varying. This signal is thus a combined VOLTAGE_SET signal and a FREQUENCY_SET signal. This sine wave is applied to the amplifier. Based on this signal, the amplifier selectively amplifies a constant signal from the power signal to generate a selected drive signal. In this version of the invention, it may not be necessary to filter this signal before supplying the drive signal output by the amplifier to the handpiece 32.

This process step can be performed in a different order than described. Thus, for the version of the invention described with reference to the flow charts of Figs. 6A and 6B, the system can be configured to adjust the frequency of the drive signal before adjusting the voltage of the drive signal. In the version of the invention described with respect to Figures 15A-15C, one of the comparisons of the ratio of the current flow through the actuator 40 to the equivalent value of the current flow applied to the mechanical component of the handpiece with respect to the target frequency Can be omitted. In this version of the invention, as a result of the execution of steps 260 and 262, this ratio is compared to a target rate that is almost always adjusted.

Likewise, there may be a change in the control algorithm. For example, the component of the algorithm used to modify the ratio between the current supplied to the handpiece driver 40 and the equivalent value of the current applied to the mechanical components of the handpiece is always the first It can not be a difference. In some versions of the invention, a second or higher order difference between the two frequencies may be used to generate a component that modifies the base rate. In another version of the invention, within a first range of differences in frequency, this component is based on a difference of one order in this frequency. Within this second range of differences at this frequency, this component is based on the difference of the second order in frequency. Likewise, in some versions of the present invention, over a range of differences in frequency, this component is based on a constant order difference in frequency. In this version of the invention, the coefficients used to determine the quadrature component may vary as a function of the frequency difference.

It is therefore the object of the claims to cover all modifications and variations that fall within the true spirit and scope of the invention.

Claims (15)

A tip (50) of an ultrasonic handpiece (32), the handpiece comprising: at least one actuator (40) to which an AC drive signal is applied to vibrate the tip,
An assembly for generating a variable AC drive signal (68, 70, 72) applied to at least one actuator (40) of the handpiece;
An assembly (80, 86) for measuring a voltage of the drive signal, the assembly (80, 86) outputting a signal indicative of a drive signal voltage;
An assembly (90, 92) for measuring a current of the drive signal, outputting a signal indicative of a drive signal current; And
A processor (96) for receiving a signal indicative of a drive signal voltage and a drive signal current indicative of the drive signal voltage, and for determining, based on the drive signal voltage and drive signal current, (96) for regulating said assembly to generate said at least one signal (68, 70, 72)
The processor comprising:
Determine (148) a target current that is an equivalence of the current to be applied to the mechanical component of the handpiece;
Based on the voltage of the driving signal, the current of the driving signal, the frequency of the driving signal, and the capacitance of the at least one driver 40, the equivalent value of the current applied to the mechanical component of the handpiece (155);
Compare the target current to a calculated equivalent value of current applied to the mechanical component of the handpiece (158);
Setting (160) the potential of the drive signal output by the assembly that generates the drive signal (68, 70, 72) based on the current comparison;
A current applied to the at least one actuator based on the voltage of the drive signal, the current of the drive signal, the frequency of the drive signal, and the capacitance of the piezoelectric driver, Calculating (164) the ratio between the equivalence of the applied current;
And to set (166) the frequency of the drive signal output by the assembly that generates the AC drive signal (68, 70, 72) based on the calculated ratio. The method according to claim 1,
Wherein the processor is configured to calculate an equivalent value of a current applied to the mechanical component of the handpiece by determining a difference between the current of the drive signal and the current through the at least one driver. The method according to claim 1 or 2,
Wherein the processor is configured to determine a current through the at least one driver as a function of the capacitance of the at least one driver and the voltage and frequency of the drive signal. The method according to any one of claims 1 to 3,
The processor comprising:
Characterized in that the calculated ratio between the current value applied to the at least one actuator (40) and the equivalent value of the current applied to the mechanical component of the handpiece is greater than the calculated value for the vibration of the mechanical component To determine if the target rate based on the target frequency and the drive frequency indicate substantially equal, and
And adjust the frequency of the drive signal if the determination indicates that the calculated rate is not substantially equal to the target rate. The method of claim 4,
The target frequency for the vibration of the mechanical component of the handpiece,
A resonance frequency of the vibration of the mechanical component of the handpiece; The antiresonance frequency of the vibration of the mechanical component of the handpiece; Or the frequency between the resonant frequency and the antiresonant frequency of the vibration of the mechanical component of the handpiece. The method according to any one of claims 1 to 5,
The processor comprising:
To obtain data indicative of the capacitance of the at least one driver (40) from the memory (58) associated with the handpiece (32); And
To calculate an equal value of the current applied to the mechanical component of the handpiece based on the driver capacitance data obtained from the handpiece memory at least at the initial activation of the system; And to calculate a ratio between the current value applied to the piezoelectric actuator based on the driver capacitance data read from the handpiece memory and the equivalent value of the current applied to the mechanical component of the handpiece, system. The method according to any one of claims 1 to 6,
Wherein the processor is configured to determine a capacitance of the at least one driver of the handpiece by setting the frequency and voltage of the drive signal. The method according to any one of claims 1 to 7,
The processor comprising:
After generating the calculated ratio between the current value applied to the driver and the equivalent value of the current applied to the mechanical component of the handpiece, calculating a ratio based on the calculated ratio, the frequency of the drive signal, To produce a modified ratio; And
And to selectively set the frequency of the drive signal based on the modified ratio. The method of claim 8,
Wherein the processor is configured to generate the modified ratio based on the calculated ratio and a difference between the frequency of the drive signal and the target frequency. The method according to any one of claims 1 to 9,
The processor comprising:
Receiving a signal indicative of a user-input command indicative of a magnitude of vibration required for the tip of the handpiece;
Wherein the controller is further configured to determine the target current based on a signal indicative of a user-indicating command indicative of a magnitude of vibration required for the tip of the handpiece. The method according to any one of claims 1 to 10,
The assembly for generating the drive signal (68, 70, 72) comprises: a power source (68) for outputting a signal at a constant frequency; and a power supply for receiving the signal output by the power supply, And an amplifier (70) configured to amplify said signal from said amplifier
The processor (96) is coupled to the amplifier to set the frequency of the drive signal by adjusting the frequency of the signal output by the amplifier. The method of claim 11,
Wherein the processor is coupled to the amplifier to set the potential and frequency of the drive signal by adjusting the frequency and amplitude of the signal output by the amplifier. The method according to any one of claims 1 to 11,
The assembly for generating the drive signal (68, 70, 72) includes a power source (68) for outputting a signal at a variable voltage;
The processor (96) is coupled to the power source to set the potential of the drive signal by regulating the voltage of the signal output by the power source. CLAIMS What is claimed is: 1. A method of regulating feeding a drive signal to an ultrasonic handpiece applied to a tissue to perform a medical procedure or surgical procedure,
Providing an ultrasonic handpiece having at least one actuator and a tip attached to the actuator for vibration by the actuator, wherein the component of the handpiece other than the actuator is a mechanical component of the handpiece, Providing an ultrasonic handpiece;
Determining a capacitance of the driver;
Determining a target current that is an equivalence of the current applied to the mechanical component of the handpiece;
Supplying an AC drive signal having a potential and a frequency to the driver;
Measuring a voltage and a current of the driving signal;
Calculating an equivalent value of a current applied to the mechanical component of the handpiece based on the voltage of the drive signal, the current of the drive signal, the frequency of the drive signal, and the capacitance of the driver ;
Comparing the target current to a calculated equivalent value of the current applied to the mechanical component of the handpiece;
Adjusting a potential of the driving signal based on the current comparison;
A current applied to the actuator and a current applied to the mechanical component of the handpiece based on the voltage of the drive signal, the current of the drive signal, the frequency of the drive signal, and the capacitance of the piezoelectric driver. Calculating a ratio between the equivalence of the values;
And adjusting the frequency of the drive signal based on the calculated ratio. A tip (50) of an ultrasonic handpiece (32), the handpiece comprising: at least one actuator (40) to which an AC drive signal is applied to vibrate the tip,
An assembly for generating a variable AC drive signal (68, 70, 72) applied to at least one actuator (40) of the handpiece;
An assembly (80, 86) for measuring a voltage of the drive signal, the assembly (80, 86) outputting a signal indicative of a drive signal voltage;
An assembly (90, 92) for measuring a current of the drive signal, outputting a signal indicative of a drive signal current; And
A processor (96) for receiving a signal indicative of a drive signal voltage and a drive signal current indicative of the drive signal voltage, and for determining, based on the drive signal voltage and drive signal current, And said processor (96) for adjusting said assembly for generating said at least one signal,
The processor comprising:
Determine (148) a target current that is an equivalence of the current to be applied to the mechanical component of the handpiece;
Based on the voltage of the driving signal, the current of the driving signal, the frequency of the driving signal, and the capacitance of the at least one driver 40, the equivalent value of the current applied to the mechanical component of the handpiece (155);
A current applied to the driver and a current applied to the mechanical component of the handpiece based on the voltage of the drive signal, the current of the drive signal, the frequency of the drive signal, and the capacitance of the driver. 262 < / RTI >
Compare the ratio between the current applied to the driver and the equivalent value of the current applied to the mechanical component of the handpiece to a target ratio (254, 264);
As a result of a comparison (254, 264) of the ratio between the current applied to the driver and the equivalent value of the current applied to the mechanical component of the handpiece to the target ratio, (256, 264);
Compare the target current to a calculated equivalent value of current applied to the mechanical component of the handpiece (260);
Adjusting the target ratio for the next comparison of the target ratio of the ratio between the current value applied to the actuator and the equivalent value of the current applied to the mechanical component of the handpiece, (262). ≪ / RTI >

Images